Heat developable photosensitive materials in which silver halides are used as photosensitive components are known in this field of technology. For example, disclosures of these materials have been made on pages 242-255 of Fundamentals of Photographic Engineering, "Non-silver Salt Edition" (published by Corona, 1982), on page 40 of the April 1978 issue of Image Report, on pages 32-33 of Nebletts, Handbook of Photography and Reprography (7th Edition, published by Van Nostrand Reinhold Company), in U.S. Pat. Nos. 3,152,904, 3,301,678, 3,392,020 and 3,457,075, British Patents 1,131,108 and 1,167,777, and on pages 9 to 15 of Research Disclosure (referred to hereinafter as RD) of June 1978.
Many methods have been proposed for obtaining color images by thermal development.
For example, methods in which color images are formed by bonding couplers and the oxidized forms of developing agents which have been formed by the reduction of silver halides have been disclosed, for example, in U.S. Pat. Nos. 3,531,286, 3,761,270 and 4,021,240, Belgian Patent 802,519 and RD 13742.
Furthermore, methods in which positive dye images are formed by thermal development using a silver dye bleach method in which silver halides are used have been disclosed in U.S. Pat. No. 4,235,957, RD 14433 and RD 15227.
Moreover, (1) methods in which diffusible dyes are imagewise formed or released from dye providing compounds along with the thermal development of a silver halide and in which these diffusible dyes are transferred to a dye fixing element which has a mordant by means of a solvent such as water, (2) methods in which transfer to a dye fixing element is achieved by means of a high boiling point organic solvent, (3) methods in which transfer to a dye fixing element is achieved by means of a hydrophilic thermal solvent which is incorporated into the dye fixing element, and (4) methods in which a mobile dye is subjected to thermal diffusion or sublimation and transferred to a dye receiving element, such as a support, have been proposed. With these methods it is also possible to obtain negative dye images and positive dye images with respect to the original, sometimes by changing the type of dye providing compound which is used and sometimes by changing the type of silver halide emulsion which is used (U.S. Pat. Nos. 4,463,079, 4,474,867, 4,478,927, 4,507,380, 4,500,626 and 4,483,914, JP-A-58-149046, JP-A-58-149047, JP-A-59-152440, JP-A-59-154445, JP-A-59-165054, JP-A-59-180548, JP-A-59-168439, JP-A-59-174832, JP-A-59-174833, JP-A-59-174834, JP-A-59-174835, JP-A-62-65038, JP-A-61-23245, and European Patents 210,660A2 and 220,746A2 (the term "JP-A" as used herein means an "unexamined published Japanese patent application")).
However, heat developable photosensitive materials of the type described above are developed at high temperatures and are therefore different from normal photosensitive materials which are developed at about room temperature. Fogging (a lowering of the D.sub.max in photosensitive materials which have a positive-positive response) occurs to a marked degree and it is difficult to obtain photographs which have high image discrimination characteristics (S/N).
Hydroxytetraazaindenes and benzotriazoles, for example, are known as anti-foggants for normal photosensitive materials which are developed and processed at temperatures close to room temperature. But the initial antifoggant objective is not achieved when these compounds are used in heat developable photosensitive materials and, moreover, they result in a loss of photographic speed.
Furthermore, heat developable photosensitive materials which have improved S/N have been disclosed, for example, in JP-A-59-168442, JP-A-59-111636, JP-A-59-177550, JP-A-60-168545, JP-A-60-180199, JP-A-60-180563, JP-A-61-53633, JP-A-62-78554, JP-A-62-123456, JP-A-63-133144, JP-A-2-44336 and JP-A-2-211442, but it has not been possible to realize objective mentioned above.
SUMMARY OF THE INVENTION
In order to realize the aforementioned objectives, a heat developable photosensitive material of the present invention comprises a support having thereon at least one photosensitive silver halide emulsion layer, wherein there is contained at least one compound selected from among the compounds represented by formulae [I], [II] and [III]. ##STR2##
In this formula, Y represents ##STR3## and R represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group. X represents --O--, --S-- or ##STR4## and M represents a hydrogen atom, an alkali metal atom, an ammonium group or a group which cleaves under alkaline conditions R' represents a hydrogen atom or a substituent group, and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each represent a hydrogen atom or an alkyl group.
Moreover, n represents 1 or 2, and m represents 4-n. ##STR5## In this formula, X' represents --O--, --S-- or --NH--. Y, R and M have the same meanings as the respective groups in formula [I].
In this formula, T and U each represent ##STR6## or --N.dbd., and R.sub.5 represents a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, a carbonamido group, a sulfonamido group, a ureido group or a thioureido group.
L represents an alkylene group, an alkenylene group, an aralkylene group or an arylene group, and l represents 0 or 1.
Y, R and M have the same meanings as the respective groups in formula [I].